Posterous theme by Cory Watilo

1.23

 

1.23

Tuesday, July 06, 2010

3:04 PM

·         1.23 recall and use the relationship between the moment of a force and its distance from the pivot: 

moment = force × perpendicular distance from the pivot

·        A moment is a turning force

·        It depends on the size of the force and the perpendicular distance from the pivot

M = F x d

 

M = moment (Nm)

F = force (N)

d = perpendicular distance from the pivot (m)

Worked example

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M = F x d

M = 1 x 5

M = 5Nm

 

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The Bunsen burner has a wide heavy base

The Bunsen Burner has a wide heavy base to make sure the chimney remains stable. It is there to provide the Bunsen Burner with support so that it does not topple over and remains standing. If the Bunsen Burner had a Thin light base, it would topple over as it will not have balance, because the base will not be strong enough to keep the chimney upright.

1.24 Answers - Centre of Mass of a Lamina

1.24 Answers - Centre of Mass of a Lamina

04 October 2010

08:47

Method

1.   Hold a pin in a clamp stand

2.   Hang a plumb line from the pin

3.   Hang the lamina shape from the pin

4.   Make sure the lamina can swing freely

5.   Draw a line along the plumb line

6.   The centre of mass is somewhere along this line

7.   Repeat steps 3 to 6

8.   The centre of mass is where the two lines intersect

 

1.24

From: Matt Baker
Sent: Tuesday, October 25, 2011 11:59 AM
To: Ahttapon Vasiksiri; Ajit Rajendran; Aleena Vigoda; Alexander Berry; Arisa Kaiho; Christina Jade Milton; Eri Sugita; Gregory Winyard; Helena Day; Karim Chen; Krishna Chaitanya Suri; Luke Jordi Oswin; Madeleine Dawn Abela; Max N. Philip; Neil Misra; Proud Chanarat; Purvi Deven Doshi; Rohan R. Iyer; Samantha Gray; Siddharth Chandrashekar; Siwaporn Sittipunt; Su-Jean Lam
Cc: maddog10physics@posterous.com
Subject: 1.24

·         1.24 recall that the weight of a body acts through its centre of gravity

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1.17 Answers to questions

1.17 Answers to questions

Tuesday, July 06, 2010

3:04 PM

1.  Sort these factors into the table below:

high speed of car, use of drugs or alcohol, poor road conditions, adverse weather conditions, poor condition of tyres, medication, badly adjusted brakes, tiredness. 

One of the above factors belong in both columns - which one?

 

Increased Thinking Distance

Increased Braking Distance

high speed of car

high speed of car

use of drugs or alcohol

poor road conditions

medication

adverse weather conditions

tiredness

poor condition of tyres

 

badly adjusted brakes

 

 

 

2.  A car is moving along an open road. Suddenly, a sheep walks into the road.

 

·         What do we call the distance the car travels before the driver puts their foot on the brakes?

o    Thinking distance

 

·         Name one factor that could increase the distance the car travels in this time.

o    high speed of car, use of drugs or alcohol, medication, tiredness

 

·         The braking distance is 35m for the car. If the stopping distance is 50m, how far did the car travel before the driver put their foot on the brakes?

o    Stopping Distance = Braking distance + Thinking Distance

o    50m = 35m + Thinking Distance

o    Thinking Distance = 15m

1.16 Answers to parachute worksheet

1.16 Answers to parachute worksheet

 

 

 

 

·         When his parachute opens, the air resistance increases

·         This is because the parachute has a large surface area

·         But his weight remains the same

·         So now there is a resultant force upwards

·         So, because of Newton’s Second Law, there is an acceleration upwards

·         So he decelerates

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·         A rain drop’s weight is constant as it falls

·         Initially, its weight downwards causes it to accelerate downwards

·         But as it gets faster the air resistance upwards increases

·         Eventually, the weight down is balanced by the air resistance up

·         When the forces are balanced it falls with a constant speed (because of Newton’s First Law)

·         This speed is the terminal velocity

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